The disclosure relates to compositions, methods, and apparatuses for recovering solvents and recycling water. More particularly, the disclosure relates to compositions and methods for recovering purge solvents and recycling spent purge water.
The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this disclosure, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR § 1.56(a) exists.
In automotive assembly plants, paint is sprayed on various vehicle components to form a protective coating for the metal and plastic surfaces. The process may include application of multiple layers of different paints, and each layer may have a unique purpose. After preparing a component for painting, the first step typically includes applying a primer and this step is generally followed by an application of base coat (color coat) and then multiple layers of a clear coat. The primer layer provides a bonding surface or interface between the metal or plastic surface and the paint. The base coat provides color and bonds to the primer. The final layer is a clear coat which seals, provides a protective layer, and produces a glossy finish.
Cars of the same model are typically available in a variety of different colors and, as a result, plants typically spray many different colors of paint. Between each color change, the paint guns and the paint lines must be purged of the paint prior to the next color being sprayed. In order to keep the paint guns clean and operational, plants may use a purge fluid. During the paint gun cleaning process, often the purge fluid is pumped through the lines and the gun for rinsing and cleaning, and then usually captured in a spent (waste) purge fluid system. Current practice is to collect the spent purge in large tanks until it can be hauled off site for disposal. Some plants may spend well up to $700,000 or more discarding this waste each year.
Purge fluid used for cleaning paint guns and paint lines typically includes about 85%-95% water and about 1-15% solvent (often a 90:10, water:solvent ratio). After cleaning, the spent purge generally comprises water, solvent, and many different chemical components, which come from a wide variety of paint formulations being sprayed. The largest component of the spent purge is water, typically greater than 90%, so plants are spending large amounts of money to transport waste water off site for treatment and disposal.
On the other hand, some plants don't have a spent purge capture system. As a result, the purge is sprayed into the recirculating water system in the same general manner as paint overspray during normal painting operations. In these plants, the purge solvent is not reclaimed or recovered. During the purge flushes, the paint is not atomized as it contacts the water and thus, the paint tends to disperse and sink in the pit rather than float for removal. The only way to remove paint from the bottom of the pit is to shut down the system, drain the water, and dig it out using manual labor.
The present disclosure addresses the aforementioned problems by providing an apparatus, methods, and compositions for treating the waste material on site, recycling the water, and recovering the purge solvent so it may be reclaimed and reused.